Plot average line using for loop iterations

I'm trying to plot a red line that is the average length of where two green line intersect and average angle to the y axis between each two of the green line iterations starting at the red point. I.e., I want to find where green line 1 and 2 intersect, the average length of the two lines up to where they intersect, the average angle of each line to the y axis up to where they intersect, and then plot a red line between the first and second green line the average of these lengths and angles, then another red line between the second and third green line, and so on. Original image is above.

img = double(mat2gray(imread('071318.bmp')));

mask_size=[5 5];
sigma=3;

Gaussian_filter = fspecial('gaussian',mask_size,sigma);

A=conv2(img, Gaussian_filter, 'same');

Gx = [-1, 0, 1; -2, 0, 2; -1, 0, 1];
Gy = [1, 2, 1; 0, 0, 0; -1, -2, -1];

SobelX = conv2(A, Gx, 'same');
SobelY = conv2(A, Gy, 'same');

gradient_direction = (atan2(SobelY, SobelX))*180/pi;
gradient_magnitude = sqrt((SobelX.^2) + (SobelY.^2));

Threshold_High = min(min(gradient_magnitude))+max(max(gradient_magnitude))*.09;
Threshold_Low = Threshold_High/2;

rows=size(A,1);
columns=size(A,2);

for i=1:rows
    for j=1:columns
        if (gradient_direction(i,j)<0) 
            gradient_direction(i,j)=360+gradient_direction(i,j);
        end
    end
end
edge_direction=zeros(rows,columns);

for i = 1  : rows
    for j = 1 : columns
        if ((gradient_direction(i,j)>=0)&&(gradient_direction(i,j)<22.5)||(gradient_direction(i,j)>=157.5)&&(gradient_direction(i,j)<202.5)||(gradient_direction(i,j)>=337.5)&&(gradient_direction(i,j)<=360))
            edge_direction(i,j)=0;
        elseif((gradient_direction(i,j)>=22.5)&&(gradient_direction(i,j)<67.5)||(gradient_direction(i,j)>=202.5)&&(gradient_direction(i,j)< 247.5))
            edge_direction(i,j)=45;
        elseif((gradient_direction(i,j)>=67.5&&gradient_direction(i,j)<112.5)||(gradient_direction(i,j)>=247.5&&gradient_direction(i,j)<292.5))
            edge_direction(i,j)=90;
        elseif((gradient_direction(i,j)>=112.5&&gradient_direction(i,j)<157.5)||(gradient_direction(i,j)>=292.5&&gradient_direction(i,j)<337.5))
            edge_direction(i,j)=135;
        end
    end
end

edge1 = zeros (rows, columns);
for i=2:rows-1
    for j=2:columns-1

        if (edge_direction(i,j)==0)
            edge1(i,j)=(gradient_magnitude(i,j)==max([gradient_magnitude(i,j),gradient_magnitude(i,j+1),gradient_magnitude(i,j-1)]));

        elseif (edge_direction(i,j)==45)
            edge1(i,j)=(gradient_magnitude(i,j)==max([gradient_magnitude(i,j),gradient_magnitude(i+1,j-1),gradient_magnitude(i-1,j+1)]));
        elseif (edge_direction(i,j)==90)
            edge1(i,j)=(gradient_magnitude(i,j)==max([gradient_magnitude(i,j),gradient_magnitude(i+1,j),gradient_magnitude(i-1,j)]));
        elseif (edge_direction(i,j)==135)
            edge1(i,j)=(gradient_magnitude(i,j)==max([gradient_magnitude(i,j),gradient_magnitude(i+1,j+1),gradient_magnitude(i-1,j-1)]));
        end
    end
end
edge2 = edge1.*gradient_magnitude;

Threshold_Low = Threshold_Low * max(max(edge2));
Threshold_High = Threshold_High * max(max(edge2));

edge_binary = zeros (rows, columns);

for i = 1  : rows
    for j = 1 : columns
        if (edge2(i, j) < Threshold_Low)
            edge_binary(i, j) = 0;
        elseif (edge2(i, j) > Threshold_High)
            edge_binary(i, j) = 1;
        elseif(edge2(i+1,j)>Threshold_High||edge2(i-1,j)>Threshold_High||edge2(i,j+1)>Threshold_High||edge2(i,j-1)>Threshold_High||edge2(i-1,j-1)>Threshold_High||edge2(i-1,j+1)>Threshold_High||edge2(i+1,j+1)>Threshold_High||edge2(i+1,j-1)>Threshold_High)
            edge_binary(i,j)=1;
        end
    end
end

edge_binary(1600:2054,:)=[];
edge_binary(:,1:300)=[];

edge_binary(602,526)=1;

ind = find(edge_binary',1,'last');
[x0,y0] = ind2sub(size(edge_binary'),ind);

ind = find(edge_binary',1,'first');
[xmax,ymax] = ind2sub(size(edge_binary'),ind);

imshow(imcomplement(edge_binary));

hold on
axis equal
title('Captive Bubble Air-Liquid Interface')
xlabel('x')
ylabel('y')
plot([x0 x0],[y0 ymax],'k')

hline_step=50;
n=round((y0-ymax)/hline_step,-1);

x=zeros(n,1);
y=x;



for i = 1:n-1
	y(i) = y0-i*hline_step;
    x(i) = find(edge_binary(y(i),:),1,'first');
    plot([x(i) x0], [y(i) y(i)],'b');
end

for i = 1:n-2
    xg = (x(i+1)+x(i))/2;    
    yg = (y(i+1)+y(i))/2;           
    yg_p = (x(i+1)-x(i))/(y(i+1)-y(i))*(xg-x0) + yg;
    plot([xg x0],[yg yg_p],'g');
end

  for i=1:n-3
     
  plot(x(i+1),y(i+1),'.r');
  end
   
x=nonzeros(x');
x=reshape(x,size(x,1),1);
y=nonzeros(y');
y=reshape(y,size(y,1),1);

plot(x,y,'r')

hold off

[Shashwat Bajpai]

I am unable to understand your question. From whatever i understood i would suggest creating a table with the average lengths of green lines and their angles with the y-axis and then plot the red lines according to your requirement. I'll be in a better position to help if you can rephrase your question.